Siemens SIMATIC S5 CP 523 Manual page 152

CP 523
7.4.2 Reading Coordination Information after "Coordinate Data Transfer"
As soon as the "Coordinate data transfer" request has been transferred to the CP, the CP 523
writes coordination information into bytes 1 to 7 of the transfer memory. This information can be
read out with load operations.
This coordination info is available in Transparent and Interpretive mode after the following
requests:
• A000 : Read status byte and coordination info
H
• A001 : Send message frame
H
• A080 : Receive message frame
H
In "3964(R) mode", different coordination info is returned when these same job requests are
issued. This info is discussed at the end of this section.
Table 7-24. Coordination Information after "Coordinate Data Transfer"
Byte
0 Status byte
1 Permission to send and receive
2+3 Message length in bytes
4+5 Irrelevant
6 Number of message frames
(calculated by the CP after a send request with fixed message
length)
7 Number of message frames in Receive mailbox
(The CP can buffer up to 100 message frames in the Receive
mailbox. The sum of the length of these messages may not
exceed 1024 bytes. When a message has been entered in the
Receive mailbox, bit 7 of byte 1 is "0".)
* Only after "Receive message" (A080
Status byte (byte 0)
In the status byte, bits 4 to 7 always have the value 5
request. Bits 0 to 3 contain error flags.
EWA 4NEB 811 6044-02a
Meaning
CPU can neither send nor receive
CPU can send and receive
*
); in the case of an illegal Send request FF00
H
Communications Mode
CPU can send
CPU can receive
H
following a "Coordinate data transfer"
H
Possible Values
5X
H
00
H
01
H
80
H
81
H
0000 to 0100
H H
0000
H
00 to 20
H H
00 to 64
H H
7-47